"Does he share the fundamental values of the average Iowan?" asked Gross.

All three candidates for the June primary have argued that Vilsack has spent the state into a deficit.

"We haven't seen any advances," Sukup said. "We're one of four states that has continued to lose population since the census."

Vilsack has not announced his intentions formally, but there's no doubt he plans to seek a second term. He recently reported he has $1.3 million in campaign funds, and has spent more than $700,000 on polling and assembling a campaign staff.

Though they declined to attack each other, each of the GOP rivals touted himself as the most formidable challenger in a matchup against Vilsack.